Water Treaters

Posted by on October 5, 2016

What sites should I test for Legionella?

I have been tasked with collecting water samples for a hospital
with three campuses. Two of the campuses have large chiller systems
with cooling towers. I am wondering what are the best samples to
take to test for Legionella.

For hot and cold potable water, should I try to test the
furthest point from the source, directly from a tap?

Sample one or two locations per floor and a minimum of ten
outlets (sinks and showers) is recommended. Along with that, sample
the hot water tanks and/or the hot water recirculating line (return
line).

Follow-Up:

Do the ice machines need testing?

Reply:

As a healthcare facility with high risk occupants, we would say
yes – test ice and water (if there is a dispenser) from ice
machines. You may have to fill a couple of bottles with ice to
provide enough water for testing.

Follow-Up:

Should I test the condensate drains from air handlers that
distribute air throughout a building?

Reply:

Generally speaking, these pans should not accumulate water and
are not a generator of significant aerosols. Pans are more often a
source of odor problems due to mold growth rather than a source of
transmission for Legionella. We do not recommend testing
these.

Follow-Up:

Cooling towers are located outside and on the roofs. Are these
potential sources of Legionella?

Reply:

Yes, cooling towers should be tested for Legionella
when operating. There are outbreaks that have been linked to
cooling towers. I’d recommend quarterly testing. For seasonally
operated towers, test during the start up, during peak demand, and
in the early fall when they may be used
intermittently.